The present invention relates to apparatus and/or process for controlling a braking force for brake assistance.
A brake assist control system is arranged to produce a braking force greater than a braking force corresponding to a driver's brake operation, by supplying, to a wheel cylinder, a brake fluid sucked from a master cylinder with a pump. During the brake assist control, the brake fluid is drained from the master cylinder by the pump, and hence the output signal of a fluid pressure sensor for sensing the master cylinder pressure does not represent a driver's brake operation quantity properly. Therefore, a driver's brake operation quantity can not be reflected adequately in a target wheel cylinder pressure in a braking force control system setting the target wheel cylinder pressure from the sensor signal of the fluid pressure sensor without using a brake stroke sensor for sensing a driver's brake operation quantity directly.
Therefore, in order to reflect a driver's brake operation in a brake assist control, a braking force control system proposed in a Published Japanese Patent Specification Publication No. 11-20638 is arranged to modify the output signal of a fluid pressure sensor with a correction quantity corresponding to a decrease of the master cylinder pressure (represented by the output signal) not attributable to the driver's brake operation.